Allow '_' in FileCheck variable names, it is nice to have at least one separate character.  - Chris, OK?
Allow '_' in FileCheck variable names, it is nice to have at least one
separate character.
 - Chris, OK?

git-svn-id: a4a6f32337ebd29ad4763b423022f00f68d1c7b7@89626 91177308-0d34-0410-b5e6-96231b3b80d8

lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx